Haven't Calvinists been arguing against free will for centuries?
I agree with Calvinists in that God's will is unchangeable. God's will is definitely not an illusion, however God cannot control our free will, but ultimately he is in control, God has predestined everything in accordance to His will. Here is an interesting analogy to explain this, however you must have a good understanding of the Bible in order to make complete sense of this.
Lets compare the true story of the Bible to a game of pool. The two main players are God and Satan. As we set up the table we see the triangle of stripe and solid balls with the 8 ball in the center. We also see the cue ball set at the head of the table ready to be used. God will go first because his plan is perfect and he uses the power of the Holy Spirit which is the cue ball. Satan has been cast out of Heaven so he is now at the mercy of God, but satan is determined to get vengeance and he thinks his plan will work and his plan is to deceive every man. The reason the 8 ball is at the center of the other balls is because satan has deceived man in the beginning and placed his evil spirit at the center of man's heart. God sets up his cue ball the Holy Spirit and breaks all the other balls apart. Every ball is confined by the laws that God has put in place so each ball will contact other balls in different ways that God doesn't actually have direct control over, He only allows it. This is a way to think about how we can have free will and even satan can have a sense of free will, though ultimately God is in control of the entire game. God makes a solid ball in on the break and so solid balls are His good men that He can work through using the Holy Spirit.
Now it's satan's turn. God allows satan to think he has power over the Holy Spirit, when in fact satan is only capable of lying and is even incapable of being true to himself. Which it does say in the Bible that God allows satan to have access to the heavenly realms and I believe the reason for this is because God allows satan to deceive man, but only for God's greater purpose which is to bring all men back to Himself. I believe the only way God can allow this is if He is willing to sacrifice Himself through Jesus Christ for the sake of man. Basically, He had to sacrifice Himself in order to get all of us back at the end in some way or another. God allows satan to think he can defeat Him, but every time satan makes a stripe ball in, it only furthers God's perfect plan without satan even knowing it, because satan can't know truth, he has no truth in him. God continues using the cue ball to sink all of his solid balls and satan continues sinking all of his stripe balls. The stripe balls can be thought of as men who've died never believing in God or the sacrifice of Jesus Christ for their sins.
It gets down to the end and satan has sunk all his stripe balls, this gives satan even more confidence that he can beat God. What satan doesn't realize is that God gets the last play and He has one solid ball left and the 8 ball is still on table, but only to give satan motivation. God allows satan's evil spirit to continue to be in the game because it is part of God's perfect plan. But God has a perfect plan that is hidden from satan. God lines up his last shot and uses the Holy Spirit to hit the evil spirit which then hits the last solid ball into the pocket and the evil spirit follows right in after it. This is the final push that I believe we are all in right now. God's last solid ball which can be thought of as the last believers in Jesus Christ on earth are all saved before the end but only after being hit directly by the evil spirit in the worst spiritual tribulation the earth has ever seen. In the end the evil spirit is destroyed by the Holy Spirit and all that's left on the table is God's perfect plan fulfilled! Satan's evil spirit, which was just a lie, a figment of satan's false imagination, has been destroyed and all thats left is satan himself. God's plan is so perfect that He is even able to destroy satan while allowing satan to have free will the entire time to think that he can win with his lies. God does this by not destroying satan directly Himself, but allowing His son Jesus Christ to destroy satan for good and for ever and ever. God was going to win ALL His people back the whole time!
This analogy suggests that God will save all men who ever lived, but also suggests that the worst of men who believed satan's lies till the end of their lives will probably have the least pleasant eternity. However, there is a major difference between believing satan's lies and believing satan is a LIAR. I believe satan is a liar, but only because God allows him to lie in order to reveal something to everyone before the end, hence the book of Revelation.
The men who believed satan's lies will have an eternity that will be nowhere near the horrific eternity that satan and his evil lie that was the false trinity will have to endure for ever and ever. Ultimately I believe all men will be saved from the suffering that satan will endure, but many are still "striped" and so God's righteous judgement will fall on them, however, I don't believe it's our place to try and speculate how God will judge these men, we have no input in the judgement while we're alive, that is God's own purpose.
This is just an analogy, take it or leave it, ultimately the truth is in the Bible which is inspired by the Holy Spirit.